MAC SE 342-0352-A ROM High duplication

[Uked31]

Hello everyone !


Before starting my first post, just to introduce myself: my name is Christophe and i live in France/Toulouse.
Passionate about retrogaming, restoration and collection of MAC SE, SE/30 and other computers and consoles such as Vectrex, C64, Amiga, Atari 2600, CBS Colecovision, Arcade cabinet,pong...;-) ...)
I have made repairs on MAC SE and SE/30 (floppy install, cleaning, electrolytic recapping/replacing by tantalum, soldering PLCC44 for 344S0063-A Audio chip,...) and will gladly share many things to support this forum !

I am restoring a MAC SE and currently struggling with a big issue with a 342-0352-A ROM High duplication.

I identified that the 342-0352-A ROM High was faulty by swapping it with the same part coming from another MAC SE.
Despite my efforts and having performed actions below, the MAC SE doesn't work :

> I dumped the original 342-0352-A ROM with a TL866II-plus (by selecting another ROM reference because not listed, Options : with no verification of the pins)
> I used a 28pin Winbond W27C512-45Z EEPROM to receive the ROM High bin
> I replaced on the logic board the duplicated ROM W27C512-45Z...and the MAC SE displayed a sad picture (00000001/0000FFFF code) meaning probably a wrong adress allocation or something equivalent.

Do you have any ideas on how to proceed ? To buy/DIY a pin adaptator 32to28pin because of pins differences ? another eproom reference ?


Many thanks for your support !!!

 

[max1zzz]

You need to use 27C010's with some rewiring on the SE, the mask ROM's are not pin compatible with anything you can buy off the shelf

If you want a neater solution I did make little adapter PCB's that adapt a 1mbit 32pin PCC EEPROM (AM29F010, SST39SF010 etc) for use in the SE that I can send you the PCB files for (Or jsut post you some assembled boards)

 

[Uked31]

Thank you for this first answer !
Could you post a picture of the adapter PCB/assembled boards ?
I would like to well understand the assembly principle and how to flash the eeprom and install it on the logic board.

 

[max1zzz]

This is the little board I made up:

I'll dig out the board schematic and layout on a little bit

 

[Uked31]

Hello, good news!
If I well understand, this PCB+AM29F010 chip can be directly programmed as is with for example (TL866II plus) and then plugged into the logic board instead of a 342-0352-A ROM?
What was the use of this assembled board from your side ?
Thanks in advance for the schematics!

 

[max1zzz]

The chip can't be directly programmed when installed in the adapter, it needs to be programmed and then soldered on toe adapter (The SE's mask ROM has extra address lines where the programming pins would normally be) but given there is no real need to update the ROM once it is programmed this is not a big deal

The schematics / board layout / gerbers can now be found here: https://github.com/max234252/SE-ROM-PLCC

 

[Uked31]

Thank you for all inputs !!! I will keep you informed in next weeks when i've made more progress !

 

[Uked31]

Hello max1zzz,
I received the PCB based on your schematics and flashed the ROM 342-0352-A High on a AM29F010B (checksum 0x014E FDA2).
Unfortunately, it does not work.
There is a sad error message (00000001 0000FFFF).
I have tested all the tracks and the 10K resistors.
Do you have any idea? Does it come from the program and the addressing area?
See some pictures attached. Thank you for your help !

 

[cheesestraws]

For what little that is worth, that sad mac error is a ROM checksum failure.

Are you sure the ROM you duplicated is good?

 

[Uked31]

@cheesestraws, the dumped ROM is coming from another well functioning Mac SE.
I also found a binary on the web that has the same checksum (Another Mac SE ROM High binary).
If anyone has another binary of this ROM 342-0352-A High, I'd like to try !

 

[psa425]

Perhaps you already tried this, but I've had this error on 2 SE's and it was the low ROM that was bad. Chip 0353-A. Have you swapped that one out with a known good one?

 

[Uked31]

Thanks for your message. Yes already tried, the only bad ROM is 342-0352-A. I just would like to know if the calculated checksum is the right one.

 

[Uked31]

@max1zzz
Thank you very much for your support !!! the 342-0352-A ROM binary file you have sent to me is the right one !
Perfect !!! all is functioning. What a nice forum !!!
Following your advice, i found this CopyRoms in order to write out a copy of the ROM from a 680x0 Macintosh to an image file.

 

[billbucks060]

Hi,
I have Mac Classic that I'm trying to fix. It displays the same error 00000001 0000FFFF.
Is there a way to fix without changing a chip ? Note that I have a BlueSCSI v2 if it helps.
@Uked31 I'm interested in the steps you carried at the end to sort the issue. Could you please send me a copy of the binary file you used ?

Thanks !